In the construction of printed circuit boards the printed circuit traces often terminate in a through hole. The through hole typically has a conductive material (i.e. tin-lead solder, gold plating) formed on the inside diameter of the hole which may also circumscribe the outer periphery of the hole. The conductive material is used to form the electrical connection with the circuit trace. In the assembly of electrical devices such as computers, it is often necessary t o connect a single through hole, or a row of through holes with other electrical components such as another printed circuit board.
In the past this has been accomplished by using connectors that include a conductive wire that is placed into and soldered to the solder or plating material around the through hole. A problem with this type of connection is that the connection is permanent. In order to disconnect such a connector from a printed circuit board the wire must be heated for removal from the hole and then resoldered for reconnection. Such a procedure is expensive and time consuming and may cause damage to the circuit board.
Other types of contacts for connecting the circuit traces to other electrical components are also known in the art. As an example, the circuit traces may terminate in a flat contact pad formed of a conductive material (i.e. tin-lead solder, gold). A non-permanent electrical connection can be made to such a contact pad using a connector having spring loaded contact beams. In general such contact beams are shaped to contact the contact pad at a single point. This concentrated force at the point of contact creates "Hertzian Stress" and is essential to the reliability of the electrical connection.
The contact point on a contact beam may be formed as a dimple that actually contacts the contact pad. The force (i.e. Hertzian Stress) exerted by the spring deflection of the contact beam is concentrated at the dimple. Such a dimple may be formed with a conical point shaped to further concentrate this biasing force and to penetrate the oxide film on the surface of the contact pad. This concentration of force at the point of contact may cause the material of the contact pad of the circuit board to cold flow around the conical point and form a gas tight seal.
The present invention recognizes that a pressure connector may be constructed to contact a through hole (or row of through holes) of a printed circuit board utilizing a non permanent spring loaded connector. Accordingly it is an object of the present invention to provide a removable pressure connector for a plated or soldered through holes of printed circuit boards. It is another object of the present invention to provide a connector having a conductor shaped to enter a through hole and electrically contact plating or solder material formed i or around the hole and to provide a concentrated force and acceptable Hertzian Stress with the through hole. It is another object of the present invention to provide a connector that is adapted to accommodate a range of through hole sizes which is inexpensive to manufacture and easy to use. It is yet another object of the present invention to provide a connector with conductors shaped to provide a locking or retention function between the connector and the printed circuit board.